Although the present invention can be applied to any vehicles, said invention and the problems on which it is based are explained in more detail with respect to a passenger motor vehicle.
In hybrid vehicles and/or electric vehicles, the power which can be output by an electric drive apparatus and an electric energy store which is assigned to the electric drive apparatus depends to a great extent on the temperature of these components. The electric drive apparatus delivers power best at a temperature which is as low as possible, and the electric energy store preferably delivers power best at a temperature of approximately 37° C. For the electric drive apparatus and the electric energy store to deliver power in an optimum way, it is necessary to control the temperature of these components.
DE 601 22 992 D2, which is incorporated by reference herein, describes a cooling apparatus for a hybrid vehicle comprising a thermal engine and at least one electric motor. The cooling apparatus comprises a cooling means for cooling the thermal engine and the electric motor, a cooler with a plurality of cooling ducts for cooling the coolant through heat exchange with an airstream, a first line between the cooler and the thermal engine in the direction of flow of the coolant and a second line between the thermal engine and the cooler in the direction of flow of the coolant. In addition, the cooling apparatus has a branch line which comprises a first branch, connected to the first line, and a second branch, connected to a line upstream of the thermal engine, wherein the branch line is suitable for cooling the electric motor, and wherein the first branch is routed via an electronic power unit and the electric motor.
U.S. Pat. No. 6,450,275 B1, which is incorporated by reference herein, describes a method and a device for cooling components of a hybrid vehicle. The device serves to cool electric hybrid components such as, for example, an alternating current system, an internal combustion engine, an electric drive unit with the associated assemblies such as, for example, a DC/DC converter, a generator and a drive motor. These components are cooled by means of a cooling system which has cooling circuits, coolers, fans, pumps, an air conditioning system compressor and a control apparatus. The pumps move the fluid through the cooling circuits, wherein the fluid takes up heat from the components, which heat is discharged by means of the coolers with the participation of the airstream of the fan. The control apparatus controls the temperature of the components by measuring the current component temperature or the corresponding coolant temperature and comparing it with a measured value of a sensor in order to switch on the fan if necessary. By monitoring the fan speed, the control apparatus regulates the airstream passing via the cooler and the air capacitor in order to keep the coolant temperature and therefore the temperature of the components within predetermined limits.